| Mineral ores are of great interest as potential oxygen carriers for the chemical looping combustion (CLC) process. However, despite their low cost, suitable ores must be selected in order to keep capital and operation cost acceptable. In that perspective, various minerals were submitted to oxidation reduction reactions in order to mimic process conditions prevailing in chemical looping combustion, as well as tested for the propensity to agglomerate in conditions of low flowing gases. The minerals were thus characterized in terms of their oxygen transfer capacity following analysis of the combustion gases and mole balance on oxygen transferred. Iron-containing minerals (ilmenite samples from various sources (Madagascar, Canada, and South Africa), as well as hematite and limonite), manganese ores (pyrolusite and psilomelane), as well as cuprite (copper), zincite (zinc), vanadinite (vanadium), millerite (nickel), brucite (fibrous and massive; magnesium), beryl (beryllium) and cobaltite (cobalt) samples were crushed, sieved and tested in a thermogravimetric analyzer, a fixed-bed and a micro-fluidized bed coupled with a mass spectrometer. Pyrolusite showed very interesting oxygen transfer capacities (value as high as 10% for reduction under syngaz at 800°C), especially when heated under oxidative atmosphere. All other minerals tested showed poor oxygen transfer capacity (below 1% (mass.) for 5 min reduction time), except for fibrous brucite (higher that 1.5% for 5 min reduction). In addition, oxygen transfer capacity tends to diminish with increasing number of cycles (except for brucite and cuprite), hence leading to very low values. Finally, iron and copper bearing minerals showed strong agglomeration tendencies. |
